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Milestone 2, added cycling through all the visible sprite tiles, though the loop runs quite a bit faster than it should

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Andrew Kesterson
2012-11-03 09:01:08 -04:00
parent 99d41cd790
commit e6885eda7c
1 changed files with 17 additions and 1 deletions
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18
nesgame.S
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@@ -165,10 +165,24 @@ _MAIN_PlaceSprites:
LDA #%00010000 ;; turn on sprites, no more background color LDA #%00010000 ;; turn on sprites, no more background color
STA $2001 ;; Write to PPU Control Register 2 STA $2001 ;; Write to PPU Control Register 2
_MAIN_loop: _MAIN_loop:
LDX #$3c ; have we gone through 60 vblanks (approx 1 sec)
CPX spritecounter
BEQ _MAIN_loop
LDX #$00
STX spritecounter
LDX $0201 ; load sprite 0's tile number
INX
STX $0201 ; increment and store it back
JMP _MAIN_loop ;; Loop forever and do nothing JMP _MAIN_loop ;; Loop forever and do nothing
NMI: NMI:
;; Let's get a look at all the different tiles. Lets change it once
;; per second!
LDX spritecounter
INX
STX spritecounter
_NMI_OAMDMA:
;; We need to copy all our OAM data to put sprites on screen during ;; We need to copy all our OAM data to put sprites on screen during
;; vblank. $2003 is the PPU OAM address, so we're going to tell it ;; vblank. $2003 is the PPU OAM address, so we're going to tell it
;; to pull OAM from $0200, and do a DMA transfer. ;; to pull OAM from $0200, and do a DMA transfer.
@@ -193,6 +207,8 @@ NMI:
palette: palette:
.db $0F,$31,$32,$33,$0F,$35,$36,$37,$0F,$39,$3A,$3B,$0F,$3D,$3E,$0F .db $0F,$31,$32,$33,$0F,$35,$36,$37,$0F,$39,$3A,$3B,$0F,$3D,$3E,$0F
.db $0F,$1C,$15,$14,$0F,$02,$38,$3C,$0F,$1C,$15,$14,$0F,$02,$38,$3C .db $0F,$1C,$15,$14,$0F,$02,$38,$3C,$0F,$1C,$15,$14,$0F,$02,$38,$3C
spritecounter:
.db $00
.bank 1 .bank 1